1. Field of the Invention
The present invention relates to color management architecture in which plural transformation modules each act to transform color data from an input side to an output side, and particularly relates to use of a phantom profile so as to transfer data from one transformation module to another.
2. Description of the Related Art
Since 1993, the International Color Consortium (HTTP://www.color.org/) has acted to promote a standardized architecture and standardized components for an open, vendor-neutral, cross-platform color management system. A representative architecture using such components is illustrated in FIG. 1. As seen there, an application 10 executing under an operating system has access to a graphics library 11 and an imaging library 12. To perform color management functionality, application 10 accesses a color management framework interface 14, which in turn has access to color profiles 15 and a default color management module 16. Interface 14 also allows access to third party color management modules illustrated diagrammatically at 17 and 18. Profiles 15 provide the color management modules with information necessary to transform color data, such as a conversion between a native device color space and a device independent color space. For each different kind of color device, different algorithmic models are described which perform transformation between the color spaces based on the color information in the color profiles 15. These algorithmic models are realized programmatically within transformation modules of the color management modules, as illustrated below in FIG. 2.
FIG. 2 shows a color management framework in which three transformation modules serially perform color transformation, each between an input side and an output side. The overall result of processing by the three modules illustrated in FIG. 2 might, for example, correspond to a transformation from an input device color space to a device neutral color space (module 1), a gamut mapping so as to ensure that colors properly are within the outputable gamut of an output device (module 2), and a transformation from the gamut-mapped device independent color space into an output color space (module 3). As seen in FIG. 2, a first module 20 derives input from a variety of different sources. For example, in the context of FIG. 2, module 20 derives input information from four different sources. First, input information is passed as a parameter from the color management framework 14 as part of an initial function call that activates module 20. Second, module 20 access data in one of the color profiles 15 which define the color information necessary to convert color data between color spaces. Third, local data 24 is maintained in an area accessible only by the module itself, such as pre-designated data specific to initialization of the module. Fourth, each module can access global data in a global data pool 25.
Recently, color management has focused on the construction of a color management pipeline in which a pipeline script defines transformation modules that apply serially, step-by-step, so as to transform color data from a given input to a target output. Because of a desire to maintain a vendor-neutral, cross-platform color management system, however, the large variety of data sources available to the transformation modules causes difficulties. For example, different platforms and different vendors might pass parameters differently from framework 14 to each individual module. And, each individual module might store data differently in global data area 25, in dependence on the vendor who wrote the module and the platform on which the module is executing. Particularly in situations where a color management pipeline is used, because the global data area 25 is the primary source of transferring data between the different modules, such a situation can lead to difficulties in data transfer and can yield unexpected and unintended color management results.
It is an object of the invention to address the foregoing difficulties through use of color transformation modules that transfer data into and out of the module through a phantom profile whose organizational format is the same as that of standardized color profiles.
Thus, according to one aspect of the invention, each of multiple color transformation modules, which can be pipelined together to yield a desired color transformation from a desired input color space to a desired output color space, includes software functionality that permits the color transform module to write profiles as well as to read them. One particular profile that is writable and readable by each color transform module is a phantom profile. The phantom profile serves as the primary conduit of data transfer between one color transform module and others, as well as the primary data conduit for transfer of data from the framework to the modules.
In particularly preferred embodiments, the phantom profile is defined in accordance with the format used by other color profiles, particularly color profiles as standardized by the ICC.
By virtue of the foregoing features, the invention provides for vendor-neutral cross-platform color management since data is transferred between color transform modules in a format corresponding to standard color profiles. Because the profiles are standardized, vendor-specific and platform-specific anomalies that might result from data transfer to a global memory area are avoided.
In particularly preferred embodiments, the color transform modules are chained together in a pipeline specified by a pipeline script which defines which modules are needed to transform the data, as well as which color profiles are needed to supply the color conversion information. Each module in the pipeline carries with it its own local data, which is managed by the transform module itself. This local data is set aside by the module when it initializes itself, and the local data is then available to the module whenever the module is actively processing image data. This local image data is available only to the transform module that uses and creates it. On the other hand, information from outside the module, such as information about the characteristics of the device or information from prior transformation modules, is provided in standardized format by a profile. Most commonly, the profiles are either color profiles which contain information necessary to transform color data, or a phantom profile which contains data accessible to all transform modules, including data passed from the framework or data passed from previous color transform modules.
This brief summary has been provided so that the nature of the invention may be understood quickly. A more complete understanding of the invention can be obtained by reference to the following detailed description of the preferred embodiment thereof in connection with the attached drawings.